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Full-Text Articles in Life Sciences
Increased Feeding And Nutrient Excretion Of Adult Antarctic Krill, Euphausia Superba, Exposed To Enhanced Carbon Dioxide (Co2), Gk Saba, O Schofield, Jj Torres, Eh Ombres, Deborah K. Steinberg
Increased Feeding And Nutrient Excretion Of Adult Antarctic Krill, Euphausia Superba, Exposed To Enhanced Carbon Dioxide (Co2), Gk Saba, O Schofield, Jj Torres, Eh Ombres, Deborah K. Steinberg
VIMS Articles
Ocean acidification has a wide-ranging potential for impacting the physiology and metabolism of zooplankton. Sufficiently elevated CO2 concentrations can alter internal acid-base balance, compromising homeostatic regulation and disrupting internal systems ranging from oxygen transport to ion balance. We assessed feeding and nutrient excretion rates in natural populations of the keystone species Euphausia superba (Antarctic krill) by conducting a CO2 perturbation experiment at ambient and elevated atmospheric CO2 levels in January 2011 along the West Antarctic Peninsula (WAP). Under elevated CO2 conditions (similar to 672 ppm), ingestion rates of krill averaged 78 mu g C individual(-1) d(-1) and were 3.5 times …
Effects Of Trophic Skewing Of Species Richness Onecosystem Functioning In A Diverse Marine Community, Pamela L. Reynolds, John F. Bruno
Effects Of Trophic Skewing Of Species Richness Onecosystem Functioning In A Diverse Marine Community, Pamela L. Reynolds, John F. Bruno
VIMS Articles
Widespread overharvesting of top consumers of the world's ecosystems has "skewed" food webs, in terms of biomass and species richness, towards a generally greater domination at lower trophic levels. This skewing is exacerbated in locations where exotic species are predominantly low-trophic level consumers such as benthic macrophytes, detritivores, and filter feeders. However, in some systems where numerous exotic predators have been added, sometimes purposefully as in many freshwater systems, food webs are skewed in the opposite direction toward consumer dominance. Little is known about how such modifications to food web topology, e.g., changes in the ratio of predator to prey …
Bioturbation In A Declining Oxygen Environment, In Situ Observations From Wormcam, S. Kersey Sturdivant, Robert J. Diaz, George R. Cutter
Bioturbation In A Declining Oxygen Environment, In Situ Observations From Wormcam, S. Kersey Sturdivant, Robert J. Diaz, George R. Cutter
VIMS Articles
Bioturbation, the displacement and mixing of sediment particles by fauna or flora, facilitates life supporting processes by increasing the quality of marine sediments. In the marine environment bioturbation is primarily mediated by infaunal organisms, which are susceptible to perturbations in their surrounding environment due to their sedentary life history traits. Of particular concern is hypoxia, dissolved oxygen (DO) concentrations ≤2.8 mg l−1, a prevalent and persistent problem that affects both pelagic and benthic fauna. A benthic observing system (Wormcam) consisting of a buoy, telemetering electronics, sediment profile camera, and water quality datasonde was developed and deployed in the …
Eelgrass Survival In Two Contrasting Systems: Role Of Turbidity And Summer Water Temperatures, Ken Moore, Erin C. Shields, David B. Parrish, R J. Orth
Eelgrass Survival In Two Contrasting Systems: Role Of Turbidity And Summer Water Temperatures, Ken Moore, Erin C. Shields, David B. Parrish, R J. Orth
VIMS Articles
Eelgrass Zostera marina L. distribution patterns in the mid-Atlantic region of the USA have shown complex changes, with recovery from losses in the 1930s varying between the coastal lagoons and Chesapeake Bay. Restoration efforts in the coastal bays of Virginia introduced Z. marina back to this system, and expansion since 2005 has averaged 66% yr(-1). In contrast, Chesapeake Bay has experienced 2% expansion and has undergone 2 significant die-off events, in 2005 and 2010. We used a temperature-dependent light model to show that from 2005 to 2010 during daylight periods in the summer, coastal bay beds received at least 100% …
Ciliate Epibionts Associated With Crustacean Zooplankton In German Lakes: Distribution, Motility, And Bacterivory, Samantha L. Bickel, Kam W. Tang, Hans-Peter Grossart
Ciliate Epibionts Associated With Crustacean Zooplankton In German Lakes: Distribution, Motility, And Bacterivory, Samantha L. Bickel, Kam W. Tang, Hans-Peter Grossart
VIMS Articles
Ciliate epibionts associated with crustacean zooplankton are widespread in aquatic systems, but their ecological roles are little known. We studied the occurrence of ciliate epibionts on crustacean zooplankton in nine German lakes with different limnological features during the summer of 2011. We also measured the detachment and re-attachment rates of the ciliates, changes in their motility, and the feeding rates of attached vs. detached ciliate epibionts. Epibionts were found in all lakes sampled except an acidic lake with large humic inputs. Epibiont prevalence was as high as 80.96% on the cladoceran Daphnia cucullata, 67.17% on the cladoceran Diaphanosoma brachyurum, and …
Characterization And Ecological Implication Of Eelgrass Life History Strategies Near The Species' Southern Limit In The Western North Atlantic, Jessie C. Jarvis, Ken Moore, W. Judson Kenworthy
Characterization And Ecological Implication Of Eelgrass Life History Strategies Near The Species' Southern Limit In The Western North Atlantic, Jessie C. Jarvis, Ken Moore, W. Judson Kenworthy
VIMS Articles
Eelgrass Zostera marina L. populations located near the species southern limit in the western North Atlantic were assessed monthly from July 2007 through November 2008. We identified (1) dominant life history strategies and local environmental conditions in southern Z. marina populations, (2) quantified differences in reproductive phenology between populations and different local environmental conditions, and (3) compared reproductive strategies to established annual and perennial life history paradigms. Observed populations expressed both life history strategies with one Z. marina population completely losing aboveground biomass and reestablishing from seeds (annual model) while another population retained aboveground biomass throughout the year (perennial model). …
Changes In Biodiversity And Environmental Stressors Influence Community Structure Of An Experimental Eelgrass Zostera Marina System, Rachael E. Blake, J. Emmett Duffy
Changes In Biodiversity And Environmental Stressors Influence Community Structure Of An Experimental Eelgrass Zostera Marina System, Rachael E. Blake, J. Emmett Duffy
VIMS Articles
Changes in biodiversity can result in decreased ecosystem functioning and loss of ecosystem services, but altered biodiversity is only one of many stressors impacting ecosystems. In many estuaries, environmental stressors such as warming water temperatures and eutrophication are increasing and negatively impacting biological communities, particularly seagrasses such as the important habitat-forming species Zostera marina (eelgrass). These negative impacts may change the diversity, composition, and functioning of this important ecosystem, but the interactions of stressors with changes in biodiversity are poorly understood. We manipulated eelgrass communities in a factorial experiment to test how changes in crustacean grazer diversity, warmer water temperatures, …
Interannual Variability Of Primary Production And Dissolved Organic Nitrogen Storage In The North Pacific Subtropical Gyre, Ya-Wei Luo, Hugh W. Ducklow, Marjorie A.M. Friedrichs, Matthew Church, David Karl, Scott C. Doney
Interannual Variability Of Primary Production And Dissolved Organic Nitrogen Storage In The North Pacific Subtropical Gyre, Ya-Wei Luo, Hugh W. Ducklow, Marjorie A.M. Friedrichs, Matthew Church, David Karl, Scott C. Doney
VIMS Articles
The upper ocean primary production measurements from the Hawaii Ocean Time series (HOT) at Station ALOHA in the North Pacific Subtropical Gyre showed substantial variability over the last two decades. The annual average primary production varied within a limited range over 1991-1998, significantly increased in 1999-2000 and then gradually decreased afterwards. This variability was investigated using a one-dimensional ecosystem model. The long-term HOT observations were used to constrain the model by prescribing physical forcings and lower boundary conditions and optimizing the model parameters against data using data assimilation. The model reproduced the general interannual pattern in the observed primary production, …
Two Decades Of Pelagic Ecology Of The Western Antarctic Peninsula, Deborah K. Steinberg, D G. Martinson, D P. Costa
Two Decades Of Pelagic Ecology Of The Western Antarctic Peninsula, Deborah K. Steinberg, D G. Martinson, D P. Costa
VIMS Articles
Significant strides in our understanding of the marine pelagic ecosystem of the Western Antarctic Peninsula (WAP) region have been made over the past two decades, resulting from research conducted aboard ARSV Laurence M. Gould and RVIB Nathaniel B. Palmer. These advances range from an understanding of the physical forcing on biology, to food web ecology (from microbes to top predators), to biogeochemical cycling, often in the larger context of rapid climate warming in the region. The proximity of the WAP to the Antarctic Circumpolar Current and WAP continental shelf bathymetry affects the hydrography and helps structure the biological community. Seasonal, …
Abundance, Composition, And Sinking Rates Of Fish Fecal Pellets In The Santa Barbara Channel, Grace K. Saba, Deborah K. Steinberg
Abundance, Composition, And Sinking Rates Of Fish Fecal Pellets In The Santa Barbara Channel, Grace K. Saba, Deborah K. Steinberg
VIMS Articles
Rapidly sinking fecal pellets are an important component of the vertical flux of particulate organic matter (POM) from the surface to the ocean's interior; however, few studies have examined the role fish play in this export. We determined abundance, size, prey composition, particulate organic carbon/nitrogen (POC/PON), and sinking rates of fecal pellets produced by a forage fish, likely the northern anchovy, in the Santa Barbara Channel. Pellet abundance ranged from 0.1-5.9 pellets m(-3). POC and PON contents averaged 21.7 mu g C pellet(-1) and 2.7 mu g N pellet(-1). The sinking rate averaged 787 m d(-1); thus pellets produced at …
Biotic Dispersal In Eelgrass Zostera Marina, Sarah E. Sumoski, R J. Orth
Biotic Dispersal In Eelgrass Zostera Marina, Sarah E. Sumoski, R J. Orth
VIMS Articles
Dispersal is a critical process in the life history of nearly all plant species and can be facilitated by both abiotic and biotic mechanisms. Despite an abundance of vertebrate fauna utilizing seagrass meadows as a feeding area and thus capable of consuming and excreting seeds, little work has been conducted on biotic seed dispersal mechanisms. The objectives of this study were to (1) determine whether seeds of the seagrass Zostera marina could pass through the digestive systems of resident and transient vertebrates of a seagrass bed and remain viable and (2) determine seed retention times in the guts of each …
Time Series Of Vertical Flux Of Zooplankton Fecal Pellets On The Continental Shelf Of The Western Antarctic Peninsula, Miram R. Gleiber, Deborah K. Steinberg, Hugh W. Ducklow
Time Series Of Vertical Flux Of Zooplankton Fecal Pellets On The Continental Shelf Of The Western Antarctic Peninsula, Miram R. Gleiber, Deborah K. Steinberg, Hugh W. Ducklow
VIMS Articles
Zooplankton fecal pellet contribution to particulate organic carbon (POC) flux over the continental shelf of the western Antarctic Peninsula (WAP) was investigated to better understand the possible effects of changes in zooplankton community structure, due to climate change, on carbon export. Fecal pellets were collected at 170 m depth in a moored sediment trap from January 2004 to January 2009. Fecal pellet shape and size (i.e., carbon content) were quantified to assess flux of pellets from different zooplankton taxa and compared between seasons and years. Fecal pellet POC constituted the dominant proportion of total POC flux, with summer (November to …
Seedling Establishment In Eelgrass: Seed Burial Effects On Winter Losses Of Developing Seedlings, Scott R. Marion, R J. Orth
Seedling Establishment In Eelgrass: Seed Burial Effects On Winter Losses Of Developing Seedlings, Scott R. Marion, R J. Orth
VIMS Articles
Constraints on the transition of seeds to seedlings have the potential to control plant dispersal and persistence. We investigated the processes leading to low initial seedling establishment in eelgrass Zostera marina through a manipulative field experiment assessing the relative importance of germination failure and seedling loss during the winter. Seed plots were established in October at 3 unvegetated sites in the Chesapeake Bay (USA) region, with seeds either at the sediment surface or buried at 2 to 3 cm. Emerging seedlings were monitored at 6 wk intervals between December and April using a video camera, and seed germination was tracked …
Ecosystem Metabolism In Shallow Coastal Lagoons: Patterns And Partitioning Of Planktonic, Benthic, And Integrated Community Rates, Juliette C. P. Giordano, Mark Brush, Iris C. Anderson
Ecosystem Metabolism In Shallow Coastal Lagoons: Patterns And Partitioning Of Planktonic, Benthic, And Integrated Community Rates, Juliette C. P. Giordano, Mark Brush, Iris C. Anderson
VIMS Articles
Net ecosystem metabolism (NEM) provides a quantifiable and integrative method for assessing the ecological responses of aquatic ecosystems to anthropogenic disturbance and has been shown to positively relate to nutrient enrichment in some systems. We measured NEM to determine the trophic status of 4 coastal lagoons receiving a range of nutrient loads on the Virginia/Maryland portion of the Delmarva Peninsula, USA. From July 2007 to July 2008, we used the component technique to assess NEM by developing photosynthesis-irradiance curves for both the water column and sediments approximately monthly; we added macroalgal incubations in the summer of 2008. We also measured …
Eelgrass Recovery In The Coastal Bays Of The Virginia Coast Reserve, Usa, R J. Orth, Karen J. Mcglathery
Eelgrass Recovery In The Coastal Bays Of The Virginia Coast Reserve, Usa, R J. Orth, Karen J. Mcglathery
VIMS Articles
Coastal bay systems are prominent features of coastlines on nearly all continents and are vulnerable to long-term environmental changes related to climate and nutrient over-enrichment. Eelgrass Zostera marina disappeared in the 1930s from the coastal bays of the Virginia Coast Reserve, USA, primarily due to a wasting disease and the effects of a hurricane. It has been re-established recently as a result of a large-scale seeding and restoration effort. The contributions to this Theme Section provide the most comprehensive account available of large-scale recovery of an eelgrass ecosystem, the consequences of the state change from a bare-sediment system to eelgrass …
Eelgrass Restoration By Seed Maintains Genetic Diversity: Case Study From A Coastal Bay System, Laura K. Reynolds, Michelle Waycott, Karen J. Mcglathery, R J. Orth
Eelgrass Restoration By Seed Maintains Genetic Diversity: Case Study From A Coastal Bay System, Laura K. Reynolds, Michelle Waycott, Karen J. Mcglathery, R J. Orth
VIMS Articles
Genetic diversity is positively associated with plant fitness, stability, and the provision of ecosystem services. Preserving genetic diversity is therefore considered an important component of ecosystem restoration as well as a measure of its success. We examined the genetic diversity of restored Zostera marina meadows in a coastal bay system along the USA mid-Atlantic coast using microsatellite markers to compare donor and recipient meadows. We show that donor meadows in Chesapeake Bay have high genetic diversity and that this diversity is maintained in meadows restored with seeds in the Virginia coastal bays. No evidence of inbreeding depression was detected (F-IS-0.2 …
Seed Addition Facilitates Eelgrass Recovery In A Coastal Bay System, R J. Orth, Ken Moore, Scott R. Marion, David J. Wilcox
Seed Addition Facilitates Eelgrass Recovery In A Coastal Bay System, R J. Orth, Ken Moore, Scott R. Marion, David J. Wilcox
VIMS Articles
Eleven years of eelgrass Zostera marina seed additions conducted in a coastal bay system where Z. marina had not been reported since 1933 have resulted in rapid Z. marina expansion beyond the initially seeded plots. From 1999 through 2010, 37.8 million viable seeds were added to 369 individual plots ranging in size from 0.01 to 2 ha totaling 125.2 ha in 4 coastal bays. Subsequent expansion from these initial plots to approximately 1700 ha of bay bottom populated with Z. marina through 2010 is attributable to seed export from the original plots and subsequent generations of seedlings originating from those …
Recovery Trajectories During State Change From Bare Sediment To Eelgrass Dominance, Karen J. Mcglathery, Laura K. Reynolds, Luke W. Cole, R J. Orth
Recovery Trajectories During State Change From Bare Sediment To Eelgrass Dominance, Karen J. Mcglathery, Laura K. Reynolds, Luke W. Cole, R J. Orth
VIMS Articles
Seagrasses are important foundation species in shallow coastal ecosystems that provide critical ecosystem services including stabilizing sediment, sequestering carbon and nutrients, and providing habitat and an energy source for a diverse fauna. We followed the recovery of functional (primary productivity, carbon and nitrogen sequestration, sediment deposition) and structural (shoot density, biomass, plant morphometrics) attributes of Zostera marina (eelgrass) meadows in replicate large plots (0.2 to 0.4 ha) restored by seeding in successive years, resulting in a chrono sequence of sites from 0 (unvegetated) to 9 yr since seeding. Shoot density was the structural metric that changed most significantly, with an …